Flax Seeds for Prostate Cancer

Why is there such a huge disparity in prostate cancer rates around the world? The incidence of malignant prostate cancer is highest in African Americans, some 30 times greater than in Japanese men, and 120 times greater than in Chinese men. The conventional thinking is that this may be due to the higher intake of animal fat and protein in the Western diet, but it could also be the protective phytoestrogens found in plant foods. There are two major types of phytoestrogens: soy isoflavones and lignans.

Researchers have found higher levels of lignans in the prostate fluids of men in countries with relatively low rates of prostate cancer, and in vitro studies show lignans can slow the growth of prostate cancer cells in a Petri dish, so a pilot study was performed on flax seed supplementation in men with prostate cancer. Why flax seeds? Because, while lignans are found throughout the plant kingdom, flax has up to 800 times more lignans than any other food.

The research team took a bunch of men with prostate cancer, about a month before they were scheduled for surgery to get their prostates removed, and put them on a relatively low-fat diet with three tablespoons a day of ground flax. Though the scientists were skeptical that they would observe any differences in tumor biology in the diet-treated patients in such a short time span, they found significantly lower cancer proliferation rates, and significantly higher rates of cancer cell death. That was compared to so-called “historical controls,” meaning compared to the kind of growth one typically sees in their situation, not to an actual randomized control group. A few years later, though, a controlled study was published.

Researchers enrolled men who recently had their prostates biopsied and were scheduled to have repeat biopsies in six months. Then, they did the same thing as the previous study: they reduced the fat in their diet and put them on ground flax seeds to see if it made their repeat biopsy look any different. These were men with what’s called PIN (prostatic intraepithelial neoplasia), which is like the prostate equivalent of ductal carcinoma in situ in the breast. That’s why they were getting repeat biopsies–to make sure it wasn’t spreading.

There hadn’t been much research on this kind of prostatic hyperplasia, with only four epidemiologic studies reported at the time. They yielded varying findings, with increased risk associated with higher energy, protein, and animal product intake, and decreased risk related to the consumption of alcohol, fruit, and green and yellow vegetables—in sum, a low-fat, plant-based diet, high in phytoestrogens. The researchers wanted to know if that kind of diet could be used to treat it too.

Watch my 4-min video Flax Seeds vs. Prostate Cancer to see what they found. Study subjects experienced a significant drop in PSA levels (a biomarker of prostate cell growth), a drop in cholesterol (what one would expect with a lower-fat diet with extra fiber), and most importantly, a significant decrease in the cellular proliferation rate. In fact, in two of the men, their PSA levels dropped so much they didn’t even have to go through with the second biopsy!

Since the dietary intervention involved both reducing fat intake and increasing flax seed consumption, how do we know the flax had anything to do with it? Given the composite nature of the intervention—both a lower fat diet and addition of flax seeds, it was unknown whether the effects could be attributed to flax seed supplementation, a fat-restricted diet, or both factors working together. To figure that out you’d have to do a study where you split men into four groups: a control group, a flax seed-only group, a lower-fat only group, and then a flax seed and lower-fat group; and that’s exactly what they did. Find out the results in my follow-up video Was It the Flax Seeds, Fat Restriction, or Both?.

That reminds me of the experiment described in Is It the Diet, the Exercise, or Both? in which researchers try to tease out the individual effects of a similar composite treatment—a plant-based diet and walking—on the growth of prostate cancer cells in vitro. They both appeared to help, but diet appeared to be more powerfully protective.

Michael Greger, M.D. FACLM, is a physician, New York Times bestselling author, and internationally recognized professional speaker on a number of important public health issues. Dr. Greger has lectured at the Conference on World Affairs, the National Institutes of Health, and the International Bird Flu Summit, testified before Congress, appeared on The Dr. Oz Show and The Colbert Report, and was invited as an expert witness in defense of Oprah Winfrey at the infamous "meat defamation" trial.

9 responses to “Flax Seeds for Prostate Cancer”

Comment Etiquette

On NutritionFacts.org, you'll find a vibrant community of nutrition enthusiasts, health professionals, and many knowledgeable users seeking to discover the healthiest diet to eat for themselves and their families. As always, our goal is to foster conversations that are insightful, engaging, and most of all, helpful – from the nutrition beginners to the experts in our community.

To do this we need your help, so here are some basic guidelines to get you started.

The Short List

To help maintain and foster a welcoming atmosphere in our comments, please refrain from rude comments, name-calling, and responding to posts that break the rules (see our full Community Guidelines for more details). We will remove any posts in violation of our rules when we see it, which will, unfortunately, include any nicer comments that may have been made in response.

Be respectful and help out our staff and volunteer health supporters by actively not replying to comments that are breaking the rules. Instead, please flag or report them by submitting a ticket to our help desk. NutritionFacts.org is made up of an incredible staff and many dedicated volunteers that work hard to ensure that the comments section runs smoothly and we spend a great deal of time reading comments from our community members.

Have a correction or suggestion for video or blog? Please contact us to let us know. Submitting a correction this way will result in a quicker fix than commenting on a thread with a suggestion or correction.

I’ve been eating 2 tbsp of gound flax seed every morning since I saw your video. Before thinking about cancer, it seems to help my chronic pain a lot. (It’s quite a relief, because I’m only 26 and I want to avoid as much as possible drugs!)

My Prostate adventure (I dug out my med records)
8/2007 PSA = 2.7 borderline OK (at age 57)
12/2008 = 4.5 rapid rise is considered troublesome
1/2009 Prostate biopsy Results no cancer
08/2011 DISCOVER PLANT BASED WHOLE FOOD UNDERGROUND
Going Vegan was surprisingly easy maintaining whole foods more difficult
09/2011 PSA = 6.5 Steadily rising PSA but I Refuse another biopsy – watchful waiting
11/2012 PSA = 5.2 lower PSA after 15 months on a plant based diet
Now in my 60s a semi-retired engineer I have cancer paranoia so…
I am 99% vegan, 90% whole food (I lapsed into being a junk-food vegan earlier this year but am now on the path.) I eat 2 tbspns flax, 1/2 tspn Amla and a handful of broccoli sprouts daily. Also white mushrooms several times a week. (The same for my wife.)
FYI those prostate biopsies have truly miserable after effects even if you do not have cancer or get a staff infection like a friend of mine who had both. For “treatment” after intravenous antibiotics they used the latest and greatest hooking up his tail to a cyclotron, shooting Protons into his prostate leaving him in diapers. But unlike me he still enjoys his barbeques. Personally I just say no. Please pass the Kale.
[Note for engineers and physical scientists: Cancer is an entropy increasing bio-process. The irony is the standard treatments increase the entropy even more. Fighting fire with fire as it were.]

Thanks for sharing! I am in a similar situation with an increasing PSA (3.8 – 4.7) and a diagnoses of PIN2 following my biopsy. Unfortunately after 6 months of a 3 tbspns of ground flaxseed daily, I saw my PSA increase from 4.1 to 4.7 so I am a bit discouraged, especially since I am already 99% vegan. However I will continue since the alternative is taking Avodart (dutasteride) which along with many side effects has “a slight” risk of high-grade prostate cancer.

Should all men take 3 tbsp ground flax every day as a preventive measure? Or would that only be advised for men who already demonstrate prostate problems?

Also, I’ve heard that there are some studies that suggest that high doses of plant ALA sources can damage the eyes. Is there any truth to that? I ask that here because it does make me worry about taking such a high dose of ground flax if there is a risk of eye damage associated.